NATURAL SCIENCES OF PHILADELPHIA. 131 



(varieties A, &c. ) are really the progressive stages of the same individuals. 

 I do not think that even the dusky stage constitutes a distinct "variety," 

 (i.e., the birds remaining in that state all through their lives ;) much less the 

 other stages. I am of opinion that every Jiiger, before arriving at full maturity, 

 passes through each of these states : beginning with a rufo-rayed plumage 

 to be presently described passing from that next into the dusky ; and then 

 assuming successively the other stages above characterized. The only ques- 

 tion is this : What age, sex, or season is this dusky stage characteristic of 1 

 I think that it comes in next after the very young rufo-rayed plumage, for 

 this reason. We find these dusky birds to be generally less robust than the 

 others; with weaker bills, less elongated central tail feathers, and parti- 

 colored tarsi. Now it is well known, that the younger the bird, the smaller 

 it is, the shorter are the central tail feathers, and the more yellow the tarsi. 

 Another argument, by analogy, is that the S. parasiticus is found in exactly 

 the same unicolor state ; and from a great number of species it can be proved, 

 I think, that in that species it supervenes directly from the rufo-rayed plu- 

 mage. [See remarks under L. parasitica.'} 



The following is the plumage of birds of the year : 



Young of Year. Bill much smaller and weaker than in the adult, light 

 colored to beyond the nostrils, when it becomes brownish-black. Feet and 

 toes mostly bright yellow, the terminal portions of the latter black. The 

 whole body is everywhere transversely waved with dull rufous. On the head, 

 neck and under parts this rufous forms the predominating color; and the 

 bands are exceedingly numerous, of about the same width as the intervening 

 dark color. On the flanks and under tail coverts the bars become wider, and 

 almost white in color. On the back and wing coverts the brownish black is 

 the predominating color ; and if any rufous is present, it is merely as a nar- 

 row edging to the feathers. The under wing coverts have irregularly-angular 

 transverse waves of brownish black and white. The remiges and rectrices are 

 brownish black, darker at their tips ; fading into whitish towards the bases of 

 their inner vanes. On the head and neck the light rufous decidedly predomi- 

 nates, and seems indistinctly but thickly nebulated with dusky ; this dusky 

 forming a conspicuous spot just at the anterior canthus of the eye. (In this 

 plumage the bird is the Stercorarius striatus of Brisson and the Larus crepi- 

 datus of Gmelin and Latham.) 



There can be no doubt that the Stercorarius striatus of Brisson. and the 

 Larus crepidatus of Gmelin and Latham, refer to this species in the very im- 

 mature state of plumage just described ; when the bird is considerably 

 smaller than when adult, and is wholly rayed with rufous and dusky, with 

 white spaces at the bases of the wing and tail feathers. The Stercorarius 

 crepidatus of Vieillot, (1817,) however, is the true parasitica, as is also the 

 Lestris crepidata, of Degland, 1838, and of Schinz, 18-10. The Lestris crepi- 

 data of Brehm (1823) is the young of the Buffoni. (Vide synonyms of 

 these species.) 



Latham in his Index, page 819, gives a "Larus crepidatus var. /?," which 

 is of course also to be referred to the young pomarinus. 



The Larus parasiticus of Meyer and Wolf is, I believe, the only instance of 

 the application of that specific name to this species. The other synonyms of 

 the species do not require any special notice, as they are quite plain and 

 uncomplicated. 



By most authors the Catharacta cepphus of Briinnich is considered as refer- 

 ring to the long-tailed species. I must confess, however, that I can hardly 

 discover grounds for &uch an identification of this name ; and am rather 

 inclined to the opinion that his cepphus is based upon the young pomarinus ; 

 as are the crepidata of Gmelin and Latham, and the striatus of Brisson. Let 

 us look at the description for a moment. It is evident, from almost every 

 paragraph of it, that he had in view a young bird of the year, in the state 



1863.] 



